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<H3>fix adapt command 
</H3>
<H3>fix adapt/kk command 
</H3>
<P><B>Syntax:</B>
</P>
<PRE>fix ID adapt Nfreq args ... 
</PRE>
<UL><LI>ID is documented in <A HREF = "fix.html">fix</A> command
<LI>adapt = style name of this fix command
<LI>Nfreq = perform grid adaptation every this many steps
<LI>args = all remaining args are identical to those defined for the <A HREF = "adapt_grid.html">adapt_grid</A> command 
</UL>
<P><B>Examples:</B>
</P>
<PRE>fix 1 adapt 1000 all refine particle 10 50
fix 1 adapt 1000 all coarsen particle 10 50
fix 1 adapt 500 subset refine coarsen particle 10 50
fix 1 adapt 10000 all refine surf 0.15 iterate 1 dir 1 0 0 
fix 10 adapt 1000 all refine coarsen value c_1<B>1</B> 5.0 10.0 iterate 2 
</PRE>
<P><B>Description:</B>
</P>
<P>This command performs on-the-fly adapatation of grid cells as a
simulation runs, either by refinement or coarsening or both.  Grid
adaptation can also be performed before or between simulations by
using the <A HREF = "adapt_grid.html">adapt_grid</A> command.
</P>
<P>Refinement means splitting one child cell into multiple new child
cells; the original child cell becomes a parent cell.  Coarsening
means combining all the child cells of a parent cell, so that the
child cells are deleted and the parent cell becomes a single new child
cell.  See <A HREF = "Section_howto.html#howto_8">Section howto 4.8</A> for a
description of the hierarchical grid used by SPARTA and a defintion of
child and parent cells.
</P>
<P>Grid adaptation can be useful for adjusting the grid cell sizes to the
current particle density distribution, or mean-free-path of particles,
or to other simulation attributes such as the presence of surface
elements.  A well-adapted grid can improve accuracy of the simulation
and/or reduce a simulation's computational cost.
</P>
<P>Adaptation is performed by this command once every <I>Nfreq</I> timesteps.
</P>
<P>All of the command arguments which appear after <I>Nfreq</I>, which
determine how adapation is done for both refinement and coarsening,
are exactly the same as for the <A HREF = "adapt_grid.html">adapt_grid</A> command.
</P>
<P>This includes a group-ID parameter which can be used to limit
adaptation to a subset of current grid cells.  See the
<A HREF = "adapt_grid.html">adapt_grid</A> command doc page for details.
</P>
<P>The one exception is that the <I>iterate</I> keyword cannot be used with
the fix adapt command.  Only a single iteration of the action1 and
action2 parameters (described on the <A HREF = "adapt_grid.html">adapt_grid</A> doc
page) can be performed each time grid adaptation is performed.
</P>
<HR>

<P><B>Restart, output info:</B>
</P>
<P>No information about this fix is written to <A HREF = "restart.html">binary restart
files</A>.
</P>
<P>This fix computes a global scalar which is a flag for whether any grid
cells were adapted on the last timestep it was invoked.  The value of
the flag is 1 if any cells were refined or coarsened, else it is 0.
</P>
<HR>

<P>Styles with a <I>kk</I> suffix are functionally the same as the
corresponding style without the suffix.  They have been optimized to
run faster, depending on your available hardware, as discussed in the
<A HREF = "Section_accelerate.html">Accelerating SPARTA</A> section of the manual.
The accelerated styles take the same arguments and should produce the
same results, except for different random number, round-off and
precision issues.
</P>
<P>These accelerated styles are part of the KOKKOS package. They are only
enabled if SPARTA was built with that package.  See the <A HREF = "Section_start.html#start_3">Making
SPARTA</A> section for more info.
</P>
<P>You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the <A HREF = "Section_start.html#start_6">-suffix command-line
switch</A> when you invoke SPARTA, or you can
use the <A HREF = "suffix.html">suffix</A> command in your input script.
</P>
<P>See the <A HREF = "Section_accelerate.html">Accelerating SPARTA</A> section of the
manual for more instructions on how to use the accelerated styles
effectively.
</P>
<HR>

<P><B>Restrictions:</B> none
</P>
<P><B>Related commands:</B>
</P>
<P><A HREF = "adapt_grid.html">adapt_grid</A>, <A HREF = "balance_grid.html">balance_grid</A>
</P>
<P><B>Default:</B> none
</P>
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